Process for treating, separating and purifying oils



May 19, 1931. E. B. AUERBACH PROCESS FOR TREATING, SEPARATING, AND PURIFYING OILS Filed Sept. 8, 1927 l lyllllllll gwwntoz W 53, (lueb/lkwli' Patented M... 19, 1931 PATENT OFFICE,

ERNST BEBTHOLD A'UERBAOH, OF BERLIN, GERMANY PROCESS FOR TREATING, SEPARATING A ND PURIFYING OILS Application filed September 8, 1927, Serial No.

This invention relates to the treatment of mineral, vegetable, marine, animal or ethereal oils for the purposes of refining, fractionating or separating such oils or mixtures thereof.

An object of this invention s to dlsclose a process by means of which oils may be treated and purified without the use of'distillation or chemical decomposition. Another object is 19 to disclose a novel method of separating oils substantially in the order of the molecular weights of constituent parts thereof. Another object is to disclose a process in which oils ma be purified without the use of heat.

An 0 ject of this invention is to disclose a process by means of which oils may be purifi ed and certain constituents separated therefrom by means of liquid carbon-dioxide.

Hydrocarbons or 011s, particularly animal, 2 marine, vegetable, ethereal and mineral oils or artificial or synthetic products of similar characteristics, produced artificially'by the distillation, carbonization or hydrogenation of carbon containing materials, are commonly purified, separated or otherwise treated by distillation into fractions of different boiling points or by chemical methods.

The distillation and refining methods known heretofore and applied to oils entail considerable losses of valuable constituents as they are accompanied generally by chemical decom osition, polymerization, resinification cracliing, and similar changes.

These drawbacks are overcome by my process which relies principally upon my discovery that oils may be purified and separated by treating them with liquid carbon-dioxide.

Briefly described, this invention comprises bringing a mixture of oils or oils with other compounds in contact with liquid carbondioxide, absorbin certain constituents or compounds from t e mixture in the liquefied gas, separating. the liquefied gas and contained absorbed constituents or compounds from the mixture of oils, and then separating the absorbed constituents or compounds from the gas. This final separation can be very readily accomplished by releasing the pressure thereby converting the liquefied gas into the vapor phase. The carbon-dioxide in gas- 'depend not only on their mazes, and in Germany September 25, 1926.

eous state may, of course, be reliquefied by any suitable means and returned to the fractionating or absorbing system in that state for reuse. In this way only relatively small quantities of liquefied carbon-dioxide are required for treating large quantities of oils or mixtures.

I have discovered that the various constituents of oils show a very definite solubility in liquid carbon-dioxide and, consequently, 68 I have invented a process of separating oils. Furthermore, I have found that my process apparently enables me to separate different oils from each other, not only by reason of the fact that the solubility of the various constituents in liquid carbon-dioxide varies in accordance with the chemical composition of said hydrocarbons, but in addition that such solubility diifers in proportion to the molecular weight of the oil. constituents. I have found that the solubility of the different products or compounds in liquid carbon dioxide chemical composition but also, with substantially the same or similar compositions, on the molecular magnitude of the product or compound. For instance, organic compounds of low molecular magnitude are much more soluble in liquid carbon dioxide ,than compounds of high molecular magnitude of the same or of a similar series. In other words, given amixture of oils of the same chemical composition a mixture of isomeric substances, I may, by my process, separate these constituents or isomers from each other.

The invention relates to the treatment of oils of all kinds with carbon dioxide for the purpose of separating them into different constituents. Oils which are embraced are chiefly mineral oils (both natural products as well as mineral oil-like hydrocarbons prepared by artificial means), also mineral oil products such as petroleum illuminating oil, lubricating oils and the like. It is also possible to treat mineral oils which have already been subjected to, distillation or washing or to treat mixtures of diflerent mineral oils of the character just mentioned.

Mineral 'oil mixtures containing fatty oils, fats or terpenes or tar oils or resin oils or 100 ketone oils or ester oils, individually or in various mixtures may also be treated. Also,

aim of distillation processes.

fatty oils, fats, terpenes, tar oils, resin oils, ketone or ester oils can also be treated separately. In all instances, the invention is used to separate these oils from one another when they are present in mixtures, and to free the oils from colored or odoriferous admixtures or constituents, which has hitherto been the In order to show what eifects can be obtained by my process, Twill give a few. ex-

amples thereof. I have treated 5 kilograms of parafline oil having a viscosity of 2.2 with 25 kilograms of liquid carbon-dioxide in a steel cylinder at ordinary temperatures. After intimate contact between the oil with the carbon-dioxide, for about fifteen minutes, the

liquefied gas was separated from the oil residue and gasified. The residualfoil, (undissolved in the carbon-dioxide and amounting. to 4580 grams) had a viscosity of 2.4:, while the constituent separated from the carbondioxide after such contact amounted to 410 grams and had a viscosity of 1.6. The vis cosities are at room temperatures unless other- .wise noted: For purposes of illustration reference may be had to the appended drawing illustrating one form of apparatus in which the processes may be carried out. The oil to be treated may be supplied to the apparatus through a valved .line 10 and by means of a pump 11 which discharges the oil to be treated by means of line 12, preferably provided with a valve 13, to'a suitable distributor head 14 within the upper portion of a pressure cylinder 15. The pressure cylinder 15 may be provided with a valved supply line 16 discharging into the cylinder 15 at the lower end'thereof. A compressor 17 receiving vaporized carbon dioxide from line 18 liquefies the carbon dioxide and such liquefied carbon dioxide may then be discharged into the pressure cylinder 15 through the valved line 16. Counter-current flow is thus established within the pressure cylinder 15, the liquefied carbon dioxide moving upwardly while the oil to be treated moves downwardly. If desired, a packing material or suitable battles may be provided I within the pressure cylinder. The liquid carpassage through the pressure 'cylinder 15 and bon dioxide extracts soluble constituents or compounds from the oil during its upward suchliquid'carbon dioxide, together with absorbed or dissolved constituents 'or compounds, is discharged from the cylinder 15' through a line 19 preferably provided with a valve'20. The line 19 may discharge into a separating vessel or expansion chamber 21, such expansion chamber being preferably maintained at a suificiently low pressure-or under such conditions of temperature and pressure as to vaporize the carbon dioxide.

The carbondioxide is then discharged from the expansion chamber 21 through a reducing valve 22 into the line 18 leading to the compressor. The constituent hydrocarbon compound or other material removed from the oil by the liquid carbon dioxide, settles to the bottom of the-expansion chamber 21 and may be drawn off periodically or continuously through the valved outlet 23. I

A battle such as the perforated plate 24, may be provided near the bottom of the pressure cylinder 15 but belowthe carbon dioxide inlet 16. Matter insoluble in the liquid carbon dioxide separates in the pressure cylinder 15,

, passing tothe lower portion of the pressure cylinder 15 below. the bafiieor plate-'24 and such insoluble matter maybe withdrawn from rape oil, after being treated with'liquid carbon-dioxide, resulted. inthe separation of pure petroleum from the rape oil, 5 kgs. of illuminating oil (consisting of 50% petroleum and 50% rape oil). were mixed at room temperature with 8 kgs. ofcarbon dioxide. After about fifteen minutes the two layers of liquid were separated and the product insoluble in liquidcarbon dioxide was again treated inthe same way with liquid carbon dioxide. The residue which remained undissolved con-,

sisted of pure rape oil (2.5 kgs.), while 2.4

kgs. of petroleum were obtained'from the carbon dioxide solutions upon evaporating the carbon dioxide. Viscosity figures mentioned hereinare those measured with Vogel-Ossags viscosimeter and are comparablewith Engler units. Again, when 5 kilograms of crude rape oil was treated with 5ki1ograms of liquid carbon-dioxide at room temperature for about 15 minutes the insoluble residue showed much less odor than the original product, while the liquid carbon-dioxide had absorbed small quantities of an ethereal oil having the odor of hay. Coal tar with a viscosity of 3.30 at 50" has been treated with three times its-quantity of liquid carbon dioxide at room'temperature and after maintaining contact betweenthe two materials for a short period of time, the liquid carbon dioxide, together with oils dissolved therein, separated from the undissolved residue. The

residual matter undissolvd in the liquid carbon dioxide was very dark in color and .of a very viscous nature, showing a viscosity of 13.46 at 50. After evaporating the carbon dioxide from the oils dissolved therein, a

light colored, low boiling oint oil was obtained having a viscosity 0 1.38 at 50. The yield of such light oil, based upon the coal tar, was about 29 percent. Crude coal tar treated with liquid carbon-dioxide produced 20 to 30 percent of its weight of a light oil which had been absorbed by the liquid gas.

Crude oil of amber having a viscosity of 6.74 at 20 C. and a specific gravity of 0.980 was treated in the manner described hereinabove with liquid carbon dioxide. A yield of 45% by weight was obtained of a fraction soluble in liquid carbon dioxide, said fraction having a viscosity of 1.57 at 20 C. and a specific gravity of 0.936. The fraction remaining undissolved in the liquid carbon dioxide had a viscosity of 31.0 at 20 C. and a specific gravity of 0.997.

No specific forms of apparatus need be described, as any suitable equipment capable of resisting the pressures required may be used. The apparatus should be capable of causing intimate mixture or contact between the liquid being treated and the liquid gas. My process may be operated continuously if desired, and and in treating a liquid the liquefied carbon dioxide may be contacted therewith singly or successively, or the liquid ma be treated with successive amounts of fres liquid carbon dioxide. The quantities of gas to be used in relation to the liquid being treated will vary with the character of the liquid and the character and amount of constituents desired to remove by solution or absorption in the liquid gas. The temperature and pressure conditions during treatment with liquid carbon dioxide may var but preferably the contacting step should e carried out at below the critical temperature and pressureconditions of liquid carbon dioxide. At room or higher temperatures the pressure employed may therefore be slightly greater than the vapor pressure of liquid carbon dioxide at those temperatures. The invention has been stated in sufiicient detail to acquaint workers in the art with its scope, and I do not desire to be limited to any specific details herein described.

What I claim is:

1. A process of fractionating oils comprising bringing said oils in contact with liquid carbon-dioxide, absorbing certain constituents of said oils in said liquid carbon-dioxide, separating the liquid carbon-dioxide from the remaining oil and then separating the absorbed constituents from the carbondioxide.

2. A process of separating oils containing constituents of different molecular weight comprising bringing such oils in contact with liquid carbon-dioxide absorbing constituents of lighter molecular weight in liquid carbondioxide, separating the liquid carbon-dioxide and absorbed constituents from the remaining oil and then separating the absorbed constituents from the carbon-dioxide.

3. A process of treating hydrocarbonic compounds comprising bringin such compounds in contact with carbon-dloxide at below the critical temperature and pressure thereof, separating such treated compounds from the carbon-dioxide and then purifying the carbon-dioxide.

4. A process of treating oils, comprlslng bringing oils in contact with liquid carbon dioxide, absorbing part of the constituents of said oils being treated in said carbon dioxide, separating the carbon dioxide and ab sorbed constituents from the remaining oil, and then separating by volatilization the absorbed constituents from the carbon dioxide.

5. A process of treating oils, comprising bringing oils in contact with liquid carbon dioxide, absorbing part of the constituents of said oils being treated in said carbon dioxide, separating the carbon dioxide and absorbed constituents from the remaining oil, separating by volatilization the absorbed constituents from the carbon dioxide, and then reliquefying and returning the carbon dioxide to the absorbing system for reuse.

6. A process of fractionating oils, comprising bringing oils to be treated in contact with liquid carbon dioxide, absorbing certain constituents of said oils in said liquid carbon dioxide, separating the liquid carbon dioxide from the remaining oil, and then separating the absorbed constituents from the carbon dioxide.

7. A process of fractionating oils comprising bringing said oils in contact with liquid carbon dioxide, absorbing certam constituents of said oils in said liquid carbon dioxide, separating the liquid carbon dioxide from the remaining oil, separating the absorbed constituents from the carbon dioxide and then reliquefying and returning the carbon dioxide to the fractionating system in that state for reuse.

8. A process of fractionating oils comprising bringing said oils in contact with l1qu1d carbon dioxide, absorbing certain constituents of said oils in said liquid carbon dioxlde, separating the liquid carbon dioxide from the remaining oil, separating the absorbed constituents from the carbon dioxide and then purifying, reliquefying and returning the carbon dioxide to the fractionating system in that state for reuse.

Sgned at Berlin this 29th day of August 192 ERNST BERTHOLD AUERBACH. 

